There isn’t much in life that comes completely free of charge, but there’s a gardening marvel that can improve your soil, feed your plants, and reduce your environmental impact without costing you a penny. In fact, it can save you money!
I’m talking about compost, the black gold that gardeners everywhere rely on to help their gardens thrive.
There’s a lot of gardening advice out there and some of it is overblown or downright worthless. But compost is the real deal.
You can easily see why this is the case if you go out into a forest and dig down into the soil. All that rich humus supporting an abundance of plant life? That’s basically soil consisting of a good portion of compost.
I stopped by the trailside on one of my runs recently and dug down into the soil where the ferns, claytonia, piggyback plants, and vine maples were thriving and sure enough the soil was rich with humus, which is nature’s compost.
Later on, I checked a spot where only dandelions were growing, and the difference was striking – the soil was notably deficient in organic matter.
Organic matter is one of the major components of healthy soil. In natural ecosystems, fallen leaves, dead plants, and animal waste decompose and enrich the soil with organic matter.
But the soil in our home gardens often lacks organic matter, and that’s because we rake up the fallen leaves, remove dead plants, and grow crops that deplete nutrients without replenishing them.
Composting is essentially a faster, more controlled version of the natural decomposition process.
In this guide, we’ll go over the basics of how to make your own compost. Here’s what I’ll cover:
What Is Compost?
Compost is partially decayed organic matter. This organic matter can be made up of many materials, most commonly food waste or scraps, fallen leaves, garden debris, and animal waste.
You’re essentially recreating nature’s compost, which is the organic matter that decomposes on the forest floor and helps plants to thrive.
Composting is the process of breaking down organic material into a medium that can be used to enrich soil. When this matter fully decomposes, it becomes humus. Yep, that same stuff that I dug up in the forest by my house.
Gardeners pay big bucks for bags of compost at the nursery or home supply store, but since all living matter decomposes eventually, you might as well put that natural process to work in your garden.
As an aside, when we use the term “organic” in this guide, we aren’t talking about the process of growing crops without chemicals. Organic in this context is a scientific term for a carbon-based material, such as plants, animals, and poop.
When we construct a compost pile, our goal is to create the perfect environment for beneficial critters to move in and break down the materials in the pile.
If you have a healthy set-up, a plethora of good bacteria, fungi, worms, nematodes, and more will help to break down the material, all while pooping out a nutritious substance that your plants will love.
Your finished compost will be rich in stuff like worm poop or castings.
A compost pile needs five components: time, moisture, air, the right temperatures, and beneficial microorganisms.
When all these components are in place, the materials therein will break down quickly. Your pile can be as complex or as simple as you wish. A simple setup would only require some leaves and veggie scraps, a bit of rain, and patience.
A more complex pile will need a careful ratio of brown to green matter, and regular turning, feeding, and watering. The reason that we maintain our piles carefully is to increase aerobic activity.
An aerobic environment is full of oxygen, which speeds up the process. The opposite is an anaerobic environment, with little oxygen.
The bacteria that break down organic matter might thrive in either aerobic or anaerobic conditions, and some can work in both.
After the materials are broken down, you’ll have what some gardeners like to call “black gold.” It’s rich, and full of nutrients to nourish your plants.
You only need a few square feet to create a decent sized pile, though you can go as big or as small as you want.
Some cities will actually take all your compostable material and turn it into compost. Then, you can go and purchase the finished material at a nominal cost.
These setups typically use hot composting in industrial machines that kill disease-causing pathogens and weed seeds in the process.
Why Compost?
Composting is beneficial for both the environment and your garden, not to mention your wallet. It acts as a fertilizer, enriching the soil and improving both drainage and water retention.
One consequence of gardening is that soil tends to become depleted over time unless we replenish it with nutrients and organic matter.
Composting creates the material you need to enrich the soil. Plus, it can help reduce your carbon footprint.
Food waste is a major problem in the US, making up about a third of our garbage. Instead of sending this waste to landfills, you can put it to work in a compost pile and reduce its environmental impact.
When food and yard waste are sent to landfill, they require trucking, which burns fuel and increases carbon emissions. Once there, the waste is buried under inorganic matter, depriving beneficial critters that could break down the waste of oxygen, moisture, and airflow.
Anaerobic organisms take over, breaking down the material and releasing biogas made up of methane and carbon dioxide into the atmosphere.
Modern landfills usually have some sort of methane capturing system, but there’s still some that escapes.
So composting helps the planet both locally and globally – but the benefits don’t stop there.
Synthetic fertilizers are made from harvested minerals that are shipped long distances for processing. These products contain only a few concentrated nutrients.
Excess fertilizer can run off into nearby waterways, causing algae blooms that deplete oxygen and kill aquatic life.
These toxic blooms have become an annual problem in some regions, harming ecosystems and local economies and even killing pets and wildlife that drink the contaminated water.
Plus, any synthetic fertilizer that isn’t absorbed by plants tends to leach out rapidly.
That means you have to keep adding it because the soil isn’t improving over time, it’s becoming more depleted. Synthetic fertilizers can also cause a crust to develop on the surface of the soil.
You can reduce excess runoff through cautious feeding and by testing your soil before you feed, but this won’t address all of the problems with synthetic fertilizers.
Compost, on the other hand, is more complete. It contains nitrogen, phosphorus, and potassium, along with calcium, magnesium, iron, zinc, and other trace elements.
You can’t always use it as a sole source of nutrients depending on your gardening practices and the plants you grow, but it can certainly act as a supplement.
In my garden, I rely almost entirely on cover crops in the legume family along with compost to feed the soil.
Potted plants or heavy feeders sometimes need a boost, but for the most part I can feed a quarter acre with just one pound of fertilizer per year, in addition to compost, cover crops, and the occasional helping of well-rotted manure.
Compost also supports beneficial microbes that have a symbiotic relationship with plants. These bacteria and fungi are essential for healthy soil and robust crop growth.
As compost breaks down, it enriches the soil, improving both water retention and drainage, allowing you to use less water when irrigating.
Compost can also help absorb heavy metals, reducing their uptake by plant roots as well as helping buffer pH, making overly acidic or alkaline soil more neutral.
Crops grown in healthy, well-fed soil are generally larger, more resistant to pests and diseases, and more nutritious than stressed ones.
While not all plants thrive in humus-rich soil – carnivorous species and many cacti prefer poor soils – the vast majority of garden plants benefit from added organic matter.
If you don’t want to dig compost into the soil, you can use it as mulch. Spread on the surface, it keeps roots cool and helps retain moisture.
Start Your Pile
You can compost indoors in a small container or outdoors in a large pile. The method you choose depends on your goals, space, and how much waste you produce.
Compost systems can take many forms: bins, boxes, wire cages, tumblers, buckets, or open piles. At the most basic, all you need is a place to put your materials.
That could be a fenced area, a wood frame, a plastic bin, or just a heap on the ground. If you plan to compost a lot of food scraps, a closed container helps keep out pests like rats and raccoons.
For indoor composting, a small lidded bucket with airflow works well. You can also buy compost bins designed for indoor or outdoor use.
Or, if you prefer the DIY route, use materials like chicken wire or scrap wood to create a containment area. That said, a loose pile will do the job.
Over the years I’ve tried just about every method, from a countertop bin to a pre-made outdoor unit to an open pile in the yard. They all work, each with pros and cons.
Personally, I prefer to have some sort of containment because it helps keep the local raccoons out and increases the heat and thus the speed of decomposition.
Some gardeners like to put a tarp or layer of plastic at the base to prevent unwanted critters from tunneling, but I don’t want plastic breaking down into my pile.
I like to put a thin layer of twigs and sticks at the base to help increase air circulation, but keep in mind that it will eventually break down and you’ll have to replace it.
Currently I use an open-bottom bin with a lid and an access door at the base for scooping out finished compost.
I add materials to the top and let my chickens help turn the pile, then harvest the stuff at the bottom as it matures.
You might need more than one pile if you intend to be constantly adding new material. One pile will be fresh material that you’re tending to and the other a pile that is close to finished or curing.
Temperature
We’re going to focus on temperature before talking about materials, because you need to decide what kind of pile you want.
There are two kinds of compost piles: cold or passive, and hot or active.
The more heat your pile generates, the faster the materials will decompose. A hot pile can break down in a matter of weeks. A moderately warm pile takes about three months. A cold pile can take six months or more.
A hot pile is full of thermophilic organisms that rapidly decompose organic matter, while cold piles contain mesophilic organisms, which work more slowly.
Hot piles should maintain temperatures between 105 and 150°F. If it goes above 150°F, it enters a danger zone where beneficial organisms can’t survive. Cold or warm piles stay below 105°F.
I have both a cold pile and a hot-ish pile. My hot pile runs at medium heat, is small, and easy to manage. It’s my go-to during the growing season when I need material for side-dressing or mulching. I keep it going year-round.
My cold pile is large and the material is mostly used for amending soil in the spring. I don’t mind if it takes a year to break down.
Hot composting takes more precision and management, while cold composting is better if you want to just toss in some ingredients and forget about it.
Consider how much effort you want to put in and how quickly you want usable material.
Also, keep in mind that sticking your hand into a hot compost pile can result in second degree burns, so you do have to use caution if you opt for that method.
If you want a thriving hot compost that you can pull from regularly, you’ll need to carefully manage your ingredients, particle sizes, and ratio, along with moisture level, aeration, and temperature. With a cold pile, you can basically leave it alone.
Speed isn’t the only advantage of a hot pile. When it reaches about 140°F, it kills weed seeds and pathogens. It also deters pests like raccoons, skunks, and rats.
A cold pile might smell bad as the anaerobic material releases ammonia, while hot piles usually don’t have a smell, or if they do, it’s generally a rich, earthy aroma.
You don’t need to be precise or test the temperature daily. If you want to check, insert a thermometer about a foot deep. I don’t test mine formally, I just feel the pile, and if it’s warm, I’m happy.
Materials
Most home piles are primarily made up of plant-based food scraps and leaves. But basically any plant-based material can go in there.
Nut shells, corncobs, thick plant stalks, pruned wood, and other large materials are fine to add, but they will take a long time to decompose.
I chip my wood before putting it in. Hay or straw is a good source of brown material, but I like to add it directly to the garden as mulch rather than using it in my compost.
I avoid citrus rinds primarily because they don’t break down easily because they have properties that can deter beneficial microbes. They will decompose eventually, but it takes a long time.
Some ingredients are controversial. I avoid citrus rinds because they break down slowly and can deter beneficial microbes. They’ll decompose eventually, but it takes time.
Pine needles are fine to add. There’s a persistent myth that they acidify compost, but that’s not true.
Coffee grounds also get labeled as acidic, but they’re not. Our guide to composting coffee grounds has more on that.
Chicken manure and bedding, and manure from animals not fed antibiotics are excellent additions.
You might hear that urea-containing materials shouldn’t be used, but once the pile heats up, that urea evaporates as ammonia. What’s left behind is beneficial organic matter.
Grass clippings are readily available and a good source of green matter, but it’s easy to overuse them. One bag can throw off the balance of a pile and turn it into a soggy mess.
I know this from experience. My husband used to toss all the lawn clippings into our pile. It took two or three times of turning a healthy heap into a stinky mess before he decided to put them in the chicken run instead.
The chickens mix them with pine shavings, so they break down a bit before we add them in moderation to the compost.
You shouldn’t compost grass clippings from lawns that have been treated with herbicides, and if there are weeds in your lawn, it can introduce weed seeds.
Speaking of weeds, be selective. You can compost most weeds and their seeds, but avoid invasive species or anything that spreads via stems or leaf fragments.
A friend once chopped up a blackberry bush and threw it into her compost. My heart sank.
Even a small section of stem can regenerate and unless the pile was nice and hot, she’d end up spreading blackberries around her garden.
She made sure that pile fully decomposed before using the material, but not everyone is that careful.
Also, thorny materials like roses or blackberries take forever to break down. You’ll be spreading sharp debris around your garden beds – not ideal if you garden barefoot or bare-handed. Best to skip thorny cane material altogether.
Eggshells are fine, though they won’t add calcium to the mix, if that’s your goal. Crush them up before tossing them in the pile.
Otherwise, they will take forever to decompose. Our guide to using eggshells in the garden has more information.
Paper products like napkins, cardboard, or newspaper can be composted, but I usually avoid them. They break down slowly, don’t offer much nutritional value, and might contain chemicals like glue, ink, chlorine, Bisphenol A, or heavy metals.
That said, I’ll sometimes toss in those compostable produce containers from the farmers market. They don’t add much, but it keeps them out of the landfill and they’re handy for collecting scraps while cooking.
Avoid using wood ash, carnivorous animal waste, dairy products, meat, fish, bones, oils, fats, or grease.
Diseased or poisonous plants should stay out as well. Technically, all of these can break down in high-heat commercial composting systems, but in a home pile, they’re more likely to cause problems.
You can add old potting soil to your compost, but it won’t contribute much.
I keep a separate bucket for used potting soil, mix it with compost at about a 4:1 ratio, and use that mix to amend garden beds or lift the soil level in a raised bed that has lost volume.
The Right Ratio
The key to speed with a compost pile is to have the right ratio of nitrogen to carbon.
Nitrogen comes from “green” materials like vegetable scraps. Carbon comes from “brown” materials like dried leaves or onion skins.
Of course, green and brown materials contain both carbon and nitrogen. “Brown” wood is mostly carbon with a little nitrogen. “Green” lettuce leaves are rich in nitrogen but still contain carbon.
A lot of gardeners will stress the importance of balancing green materials to brown materials, but it’s really all about balancing nitrogen and carbon.
The labels “green” and “brown” are just shorthand – they’re not perfect. Manure, for example, is brown in color but counts as a “green” material. Alfalfa is green in color but considered “brown” material.
For ideal decomposition, aim for a 30:1 carbon-to-nitrogen ratio by weight – 30 pounds of carbon to one pound of nitrogen.
This balance supports the microbes that break down organic matter quickly and effectively. If the balance is off, those beneficial organisms might not have the nutrients they need, which gives less helpful microbes an opportunity to take over.
So how do you calculate that? For reference, fallen leaves are about 25 percent carbon to 1 percent nitrogen.
Kitchen scraps contain roughly equal parts carbon and nitrogen. Yard waste is around 40 percent carbon to 1.3 percent nitrogen.
Now, you could get out your calculator, weigh every ingredient, and carefully balance the numbers.
Just kidding.
Unless you’re working with a small indoor bucket, calculating the exact ratio isn’t practical for most people. And I don’t do it either. Instead, I aim for a rough balance using volume: one part brown to one part green. That usually gets the job done.
You don’t need to worry about the ratio at all if you aren’t in a hurry. A pile made from pure nitrogen like lettuce scraps and grass clippings will decompose eventually, it will just take a long time.
That’s why I choose to have several piles, because then I can have one that has the perfect ratio and decomposes quickly, while the other one can take all the other materials I need to get rid of.
Moisture
Moisture is critical to a healthy compost pile and decomposition can’t happen without it. The pile should always feel like a well-wrung-out sponge – not soggy, not dry.
In wet weather, you might not need to add any moisture. If conditions are too wet, you might need to cover the pile.
During the dry months, you might need to get out there with a hose. If you have a cold pile, watering may not be necessary. If it’s allowed to dry out, decomposition will slow or even stop, but things will pick back up when the rain returns.
Avoid leaving your pile exposed to frequent rainfall. Not only does this make the pile too wet, but it flushes out the nitrogen.
If you have a moisture meter, aim for a moisture level of 45 to 50 percent. Outside of that range, aerobic activity will stall.
You don’t need a fancy tool to determine moisture, though. Just grab a handful and squeeze. If one or two drops come out, you’re in the sweet spot. If nothing comes out, it’s too dry. If water runs out, it’s too wet.
To cover your pile, place a few sticks on top to create a tent for a tarp or sheet of plastic. Or use a bin with a lid. Since I get a lot of rain where I live, I use a lidded bin and just pop the lid on or off as needed.
Turning the Pile
You’ve probably seen those rotating compost bins. The purpose of that rotating feature is not just to mix up the materials but also to introduce air into the pile.
Think of compost as a living, breathing system. Without air, it can’t survive.
Air will naturally enter the pile to some degree but keeping it well-aerated will speed up decomposition. It’s particularly important when you’re creating a hot pile.
To speed up the process, turn the pile frequently. How often you do so will depend on what temperature you’re trying to achieve and the size of the pile. Air can only reach about 18 inches deep on its own.
Some gardeners opt to put a wire tube down the center of the pile to increase airflow.
If your pile starts to smell or stops decomposing, it needs to be turned. If the temperature reaches 145°F, it’s becoming too hot and should be turned to cool it down.
I turn my hot pile maybe once a week and my cold pile once a month, if that.
To turn your pile, you can use a pitchfork, shovel, rake, or a compost aerator tool. With a rotating bin, just give it a spin once a week or so. I’ve got a secret weapon – my chickens.
They jump into the bin and kick things around, helping to mix it up. I follow up with a pitchfork to stir the deeper layers they can’t reach.
Another option is to use a three-bin system. The first bin is for the fresh materials. As they break down and need a turn, you move them into the second bin.
As they decompose further in the second bin and need another turn, move the material into the third bin where it finishes. The third pile is where you pull from and the first pile is where you add fresh material.
Using Compost
You’ll know it’s time to dig into your pile and start spreading it around the garden when you can no longer identify the original materials.
If you poke around, you shouldn’t be able to see distinct leaves or bits of peas and onion skins from the kitchen. Nut shells or twigs might still be visible and that’s fine – they take longer to break down.
If you’re planning to use the compost as mulch, you don’t have to wait for it to fully decompose. But if you want to work it into the soil, let it reach that soft, crumbly, loose texture.
Not sure if it’s ready? Try planting a few fast-germinating seeds like lettuce in the compost. If they sprout and grow, it’s good to go.
If you don’t need to use your compost right away, let it cure for a few weeks or months. Immature compost can have high levels of acid, nitrogen, or carbon. Curing lets it settle a bit and become balanced.
This isn’t such a big deal if you’re spreading compost in garden beds, but it’s important if you’re using it in pots or containers.
I like to say there’s no such thing as too much compost. But of course, that’s an exaggeration.
Healthy soil is made up of air, water, sand, silt, clay, and organic material – with organic matter making up the smallest portion.
If you added too much, you would upset this balance, creating an environment with too much moisture and not enough air.
There’s also the issue of nutrients. Compost tends to have a balanced NPK (nitrogen, phosphorus, potassium) ratio, but most plants need more nitrogen than what compost alone can provide.
So while the addition of some compost is great, more isn’t necessarily better. If you want to work it into the soil or use it as mulch, keep it to about an inch.
Cautions
Hot compost piles can reach temperatures well above 131°F, which is hot enough to cause second-degree burns.
So don’t stick your bare hands into the pile or you could get seriously injured.
Unless you have a commercial composter or a massive pile, spontaneous combustion isn’t a concern. Home piles simply don’t reach the necessary temperatures. If you see “smoke” rising from your compost, it’s likely just steam.
For combustion to occur, internal temperatures need to approach 300°F, and the pile would have to be massive – hundreds of feet long or over 50 feet tall.
Moist piles are less likely to combust than those full of dry materials. Piles that have combusted are also usually low in oxygen, high in methane, and extremely rare in home settings.
You’re far more likely to see a hay pile catch fire. I’ve seen hay combust and take out half a barn, but even the hottest backyard compost pile hasn’t come close.
If your pile smells bad, something’s wrong. A healthy compost pile should smell earthy, like the forest floor. A foul odor is a sign the balance is off, or there’s too little oxygen in the mix.
Don’t be alarmed if you see critters like worms and insects in your compost pile. These are usually a good thing!
Ants, beetles, centipedes, snails, worms, and more will get in there and chomp up that organic matter. As they feed, they transport healthy bacteria throughout the pile and add nutrients with their waste. Welcome these living beings to your pile.
What you don’t want are rodents. I personally don’t care if raccoons or bears paw through my pile, but rodents carry diseases that may not be destroyed by the composting process, especially if your pile doesn’t get hot.
Plus, rodents can burrow in and hide in the pile, and it’s an unpleasant surprise to have a rat book it across your bare toes. Or so I’ve heard.
Let’s Go Digging For Black Gold
I think you can tell that I’m a huge fan of compost. It doesn’t have to be time consuming or complicated to make your own.
You can go as simple or complex as you want. Composting uses up waste and gives you black gold in return.
So, what kind of pile will you build? Maybe a small tumbler for your backyard beds, or a three-bin setup to fuel your farm? Let us know your composting plans in the comments section below!
Now that you’ve reached this point, keep going on your composting journey with the following guides:
